Other Important Reactions of Carboxylic Acids


Sodium salts of carboxylic acids undergo decarboxylation to form alkanes when distilled with soda lime (NaOH + CaO).

Decarboxylation in carboxylic acids

Hell-Volhard Zelinsky (H.V.Z)

α-substituted carboxylic acids are formed when carboxylic acids react with Cl2 or Br2 in the presence of red phosphorus. This reaction is known as Hell-Volhard Zelinsky reaction or in short H.V.Z reaction.

Hell-Volhard Zelinsky reaction in carboxylic acids

Important points regarding Hell-Volhard Zelinsky reaction

Electrophilic Substitution Reactions in Aromatic Acids

Aromatic carboxylic acids undergo electrophilic substitution reactions such as halogenation, nitration and sulphonation. Since the -COOH group is electron-withdrawing, the substitution occurs at meta position. The -COOH group is deactivating, therefore, the reactions take place under drastic conditions.


Electrophilic substitution reaction in carboxylic acids : nitration


Electrophilic substitution reaction in carboxylic acids : sulphonation

Friedel-Carfts reactions

Benzoic acid does not undergo Friedel-Crafts reactions because -COOH group is strong electron attracting group and deactivates benzene ring for alkylation and acylation.


Convert benzene to m-nitrobenzoic acid.